Serious question, cause I’m confused.

Does your period change when you become sexually active? I lost my virginity to my boyfriend about 6 months ago, we are very active with one another and I noticed my cycle has changed a lot. It’s not consistent, it can be up to a week late sometimes; it’s just always starting at different times now. Also, it’s not as long, it used to be 4-5 days now it’s more like 3? My flow isn’t as heavy, like isn’t nearly as heavy as it used to be. This past cycle I’m on, it was 4 days late and it was like I had blood in me that wasn’t coming out, then we had sex and I went to pee and there was blood suddenly. Almost like he started my period? Or we had sex unknowingly on my period? Idk. I’m confused and I feel like I don’t have a confident understanding of my cycle anymore.